Evidence map›Paper›PMID 41634930›Full record

ArticleClinical and experimental otorhinolaryngology2026

Effects of Neonatal Deafness on Central Tonotopic Organization in Rats: an Electrophysiological Study.

Woongsang Sunwoo, Yeeun Kim

Abstract read
In one paragraph

Article in Clinical and experimental otorhinolaryngology, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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4 · The record

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5 · Who and what money

Authors and funding

2 authors.

Woongsang SunwooGachon Biomedical Convergence Institute, Gachon University Gil Medical Center, Incheon, Korea. sunwoowoongsang@gmail.com.
Yeeun KimGachon Biomedical Convergence Institute, Gachon University Gil Medical Center, Incheon, Korea.

Funding

Gachon University Gil Medical Center FRD2022-04Ministry of Science and ICTNational Research Foundation of Korea RS-2024-003345850102
6 · The paper itself

Abstract

objectivesSpatial mapping of sound frequencies along the auditory pathway is refined through sound-evoked activity during early development. However, how neonatal auditory deprivation alters this organization remains unclear. This study examined frequency-specific spatial representations in the inferior colliculus (IC) using targeted low-frequency (apical) and high-frequency (basal) cochlear stimulation, enabling direct evaluation of low-frequency pathway integrity after neonatal deafness.

methodsSixteen Sprague-Dawley rats (8 normal-hearing [NH] and 8 neonatally deafened [ND]) were studied. Neonatal deafness was induced by daily kanamycin injections from postnatal days 4 to 17. At 8-10 weeks of age, all animals underwent unilateral cochlear implantation with bipolar electrode pairs positioned in apical and basal cochlear regions to activate low- and high-frequency pathways. Multiunit responses were recorded from the contralateral IC using a multichannel linear electrode array. Spatial tuning curves (STCs) based on cumulative discriminability were used to assess thresholds, spread of excitation, and tonotopic precision. Spiral ganglion neuron (SGN) density was quantified histologically.

resultsDespite 48%-67% SGN loss across cochlear turns, electrically evoked auditory brainstem response thresholds and IC thresholds were comparable between groups, indicating preserved peripheral excitability. However, ND rats exhibited significantly broader STCs (P=0.002) and reduced dorsoventral separation of apical and basal best sites (1.18± 0.67 mm vs. 1.80±0.40 mm, P=0.039), reflecting degraded central tonotopic precision. The effects were most pronounced for apical (low-frequency) stimulation, consistent with the selective vulnerability of low-frequency pathways to early auditory deprivation.

conclusionThese findings provide direct physiological evidence that early auditory experience is critical for refining frequency-organized connectivity in the auditory midbrain. The preferential degradation of apical (low-frequency) spatial tuning offers translational insights for optimizing stimulation strategies in early-onset deafness.

Indexed as

Auditory PathwaysCochlear ImplantInferior ColliculusNeonatal DeafnessNeuronal PlasticityRat

Identifiers

PMID41634930
PMCPMC13555250

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.